In manufacturing of a product, the product is processed at many work stations or processing machines. These work stations are usually clustered into process bays. Interbay or Intrabay conveying of work-in-process (WIP) parts or semi-finished products typically involve the use of an automatic guided vehicle (AGV) system, a rail guided vehicle (RGV) system, an overhead transport (OHT) system, and/or human labor. Stockers are usually installed in between process bays or within process bays to, for example, provide a buffering space for the WIP parts between work stations. AGVs, RGVs, OHT vehicles and/or human labor are used to transport the WIP parts between work stations and a stocker. However, waiting time for the AGVs, RGVs, OHT vehicles and/or human labor to pick up or drop off WIP parts at the stocker can be affected by poorly coordinated scheduling of the vehicles and a robotic arm mechanism of the stocker and by traffic condition on a route to or from the stocker and so on and can cause undesirable delays that affect a throughput of the product.
Like reference symbols in the various drawings indicate like elements.